1. Field of the Invention
The present invention relates to an opening and closing mechanism for a battery compartment, and a cover of a water-proof structure for a battery compartment.
2. Description of the Related Art
In a known cover which opens and closes an opening of a battery compartment, the cover is rotated between an unlocking position in which the cover is detachably attached and a lock position wherein the cover cannot be removed. A battery received in the battery compartment is biased in a discharge direction by a resilient piece constituting an electrical conductor, so that the cover can be easily moved upward in the unlocking position. However, if a cover having a seal member such as an O-ring is used to close a battery compartment of a water proof/drip-proof device, it is difficult to detach the cover even the cover is positioned at the unlocking position. The seal member is elastically deformed to seal the battery compartment in a water-tight fashion when the cover is in a lock position. If the cover is in a locked state for long time, the seal member tends not to be restored rapidly from a deformed state. Consequently, the cover does not tend to move upward (open) in the unlocking position, and hence, it is necessary to forcedly insert a tool having a sharp end between the cover and the opening of the battery compartment in order to open the cover. When no battery is loaded in the battery compartment, since there is no biasing force acting on the battery, the cover tends not to open. If a mechanism which makes it possible to always forcedly detach the cover in the unlocking position is provided, the cover has a tendency to be accidentally detached, and thus, the cover can be easily lost or damaged. Under these circumstances, it has been necessary to provide an opening and closing mechanism for a battery compartment in which a forced open position in which the cover can be forcedly opened and a normal unlocking position can be selected.
Moreover, there is a problem with the cover itself. Namely, the cover for a battery compartment of a water-proof and drip-proof structure must be provided with a receiving portion in which an elastic seal member such as an O-ring is held, so that the seal member is exposed to the peripheral surface of the cover. The receiving portion for the elastic seal member can be obtained by forming an annular groove on the peripheral surface upon forming the cover body. Alternatively, the receiving portion can be obtained by forming a projection in the form of a rib on the peripheral surface of the cover body, so that another member which defines opposed wall surfaces is secured to the projection by means of screws, etc.
To form an annular groove on the peripheral surface of the cover body, expensive sliding dies must be used. In addition, a parting line of the dies extends across the annular groove, i.e., the elastic seal member receiving portion. Since a stepped portion or a burr tends to occur at the parting line, a gap between the elastic seal member and the annular groove tends to occur, thus resulting in a failure to seal properly. On the other hand, in the above mentioned alternative, the screws must be used to attach the separate member which defines the opposed wall surfaces to the cover body, thus resulting in an increased number of assembling processes and an increased manufacturing cost. Therefore, there is a need to provide a cover of waterproof/drip-proof structure for a battery compartment cover which is free from the above mentioned drawbacks.